The present invention relates to an electromagnetic flowmeter for simultaneously measuring the flow rate and the conductivity of a fluid.
A flowmeter, such as an electromagnetic flowmeter, is used to measure a conductive fluid. In recent years, demand has also increased for information as to the characteristics of a fluid, such as conductivity, in addition to the flow rate thereof.
Conventional electromagnetic flowmeters which only measure the flow rate, for example, as disclosed in JPA-63-6420 and as shown in FIG. 1, require a separate measuring instrument if the conductivity of a fluid is to be measured, thereby complicating the construction of the entire system.
In the flowmeter shown in FIG. 1, a fluid flows in a measuring pipe 1. An excitation coil 5 is excited by a pulse excitation current generated in an excitation circuit which is controlled by a timing circuit 6, and the resulting magnetic fluxes are applied in a direction substantially perpendicular to the flow of the fluid. A voltage induced within the fluid by the magnetic fluxes is detected by a pair of electrodes 2a, 2b, and after being amplified by an amplifier 3 and sampled by a sampling circuit 7, an output signal representing a flow rate is produced at an output circuit 8.
In this electromagnetic flowmeter, detection of the conductivity of a fluid, such as the degree of turbidity of water, requires separate, exclusive measuring means, thereby complicating configuration of the entire system and increasing a product cost.